N-Boc-L-pyroglutamic acid benzyl ester is a protected derivative of L-pyroglutamic acid, featuring both a tert-butoxycarbonyl (Boc) protecting group on the amine and a benzyl (Bn) ester protecting group on the carboxylic acid. This white to off-white crystalline solid is a chiral, non-racemic building block with a molecular formula of C17H21NO5. This compound serves as a crucial protected intermediate in the synthesis of complex peptides and peptidomimetics. The Boc group is acid-labile, allowing for orthogonal deprotection strategies commonly employed in solid-phase peptide synthesis (SPPS) and solution-phase chemistry. Its primary application is in the pharmaceutical research and development of bioactive molecules, particularly those containing the pyroglutamate moiety, which is found in various neuropeptides and hormones. As a versatile chiral synthon, it is widely used in academic and industrial laboratories to introduce the (S)-5-oxopyrrolidine-2-carboxylic acid scaffold into target structures. It is commercially available from multiple fine chemical suppliers for research purposes. Standard precautions for handling organic compounds should be observed.